Currently, solid axles for trains are inspected from their front faces using single-element ultrasonic (UT) probes with different angles or phased array (PA) UT probes with an electronic steering capability. During the inspection the axles are typically already mounted on the trains and equipped with relevant components, for example, wheel-sets, brake disks, transmission disks, etc.
Inspection of the axles requires that as much volume as possible of the axle is inspected. However, in most cases, the axle's skin surface is protected with a thick paint that makes a proper UT coupling impossible. The only free access point for inspection is thus the axle's front face. However, as shown in FIG. 1, threaded holes 10 formed in an axle's front face for fixing a cap to the axle prevent certain areas or angular sectors 12 from being inspected. PA probes currently exist which can be inserted in a cone-shaped stud hole 14 formed in a front of face of an axle, as illustrated in FIG. 2, but these probes can only be used for testing the front journal or the wheel set area of the axle, and it is not possible to cover the body of the axle (e.g., the central part of the axle's shaft).
During inspection with single-element UT probes, A-Scan data is conventionally used in testing, which limits the comprehensive documentation of the testing results. Additionally, due to the limited amount of inspection angles used, and thus limited testing coverage, indications may be missed or wrongly estimated. Since the inspection with single-element UT probes requires a repetition of the axle for each probe, the testing with the probes is typically time consuming.
Also, a challenge in the inspection of solid axles from the front joint either by PA or single-element UT probe are geometrical reflections from the axle itself which may mimic or hide reflection signals from relevant indications and the multiple reflections plus mode conversions which may cause false indications.
Accordingly, there remains a need for improved methods, systems, and devices for solid axle testing.